Take the guesswork out of trailer wiring with this innovative 4-pin flat circuit tester. This practical device combines three essential functions in one compact unit: a circuit tester, plug mount, and plug saver. The built-in red LED indicators clearly show proper electrical connections, making it easy to verify your trailer's lighting system is working correctly. When your trailer isn't in use, this device serves as a secure storage solution for your 4-way flat connector, keeping it protected from the elements with its water-tight seal. The durable construction ensures long-lasting performance in various weather conditions. Perfect for both professional mechanics and DIY enthusiasts, this tester helps maintain proper trailer lighting function while extending the life of your wiring connector. Simple to use and interpret, it's an indispensable tool for anyone who regularly tows trailers, boats, or other recreational vehicles.